Noticed these problems when V28 launched but might have been prior as well.
When in Link Mode: Using the same cable USB in same slot I have always used (have now tried other usb slots) I have noticed at least two horizontal thin black lines dividing the screen in thirds. They are the sort of thing that "once you see it you can't unsee it". There also appears to be a very slight visual difference between each section with the section above the top line being blurry, the mid section appears to be sharper and the bottom section slightly darker and better looking overall. This is most noticeable when looking into the distance on large games when the sky is somewhat overcast or the background is lighter in color.
When in AirLink Mode (Experimental): The same lines exist as in the normal link mode as listed above, but there is a VASTLY annoying "Wipe" that occurs across the lenses. This looks like a vertical windshield wiper (actually a slow moving vertical black line) slowly moving from the left edge of the left eye across the lens and then from the left edge of the right eye all the way across that lens and then it constantly repeats. I have noticed this effect each time I play fallout 4 from the same location (used to test for quality).
I have tested for these problems with the headset being just turned on and with about an hour of play time and they are always there regardless.
These problems do not show up when using the Virtual Desktop program (sorry), nor do these lines show up in the Quest 2 headset for games stored on that headset. The problems were noticed on the V28 and V29 updates.
Did not spend much time in Link during V26 and V27 updates to really notice the problems.
Further tests show it is not affecting my Oculus games (that I have found so far) but just SteamVR games most notably Skyrim VR and Fallout 4 VR (the only two so far in fact). I tested Asgard's Wrath, an Oculus game, and Karnage (a Steam Game) in an area where the conditions were similar to the areas I noticed the problems in Fallout 4 VR and Skyrim VR (overcast or snowy) and found no problems were noticeable. I had made sure to remove Steams version of supersampling as it may be on the steam side and that is 1 variable I could remove. On a side note, being tired at seeing the blurry textures in games with AirLink I slammed the Resolution slider in the Link to Max and restarted. Oddly, the map I went back into was nice and clear (same map) and SMOOTH. I thought Airlink did not use the Link settings? Normally when you raise the resolution like that you get a bad case of jitter. Yes the lines were there and the wiper was there.